This invention relates to air conditioners and heat pumps and in particular to self contained packaged air conditioner and heat pump units which include both indoor and outdoor coils and a pair of blowers.
Conventional packaged air conditioners and heat pumps generally include both a conventional centrifugal blower for the indoor heat exchanger and an axial blower for the outdoor heat exchanger. All conventional packaged terminal air conditioners also include some type of dividing wall which divides the indoor portion of the unit from the outdoor portion of the unit. Air is conventionally drawn into the unit through the sides, the rear, the outside face, or the bottom of the unit and is blown out of the unit after passing over the heat exchangers.
Some prior art air conditioners have included tangential or cross flow blowers for the indoor heat exchanger. U.S. Pat. No. 4,478,053 discloses an air conditioner which includes two vertically mounted cross flow blowers, one of which is used to move air across the indoor heat exchanger and the other which is used to move air across the outdoor heat exchanger. This patent shows separate motors for driving the two blowers. Other prior art air conditioners have used centrifugal or axial flow blowers.
Several problems have been encountered with the prior art air conditioners with axial flow fans and centrifugal blowers described above. One problem is the significant cost of providing a separate motor for each blower. Another problem is that the air flow through or across the heat exchangers is non-uniform due to the non-uniform performance characteristics of prior art blowers whereby hot spots develop in the heat exchangers, thus causing the heat transfer process to be less efficient than desired.
Another problem with these prior art air conditioners has been that they are rather noisy. The noise is primarily created by the air flow through the unit because prior art centrifugal or axial flow blowers generate substantial expansion and contraction of the air and cause impact of the blower blades upon the air. Such noise is particularly undesirable as packaged air conditioners are commonly used in dwelling places, either by mounting through a wall or in a window.
Another problem with prior art self contained air conditioners has been that, due to the types of blowers used, the depth dimension of the unit is much greater than is desired. Thus the prior art units tend to take up much more space in the dwelling than is desired.
U.S. Pat. Nos. 3,200,609 (Laing) and 3,301,003 (Laing) disclose air conditioners which use two cross flow blowers. Both of these patents disclose air conditioners with various arrangements of the evaporator and condenser coils and of the cross flow blowers. Each side of the air conditioner has a heat exchanger coil in communication with the indoor or outdoor air, respectively. Cross-flow blowers are positioned in respective interior regions for inducing air flow through approximately half of the heat exchanger and for forcibly blowing air through the other half of the heat exchanger. The respective interior regions are located on opposite sides of a divider wall which includes additional curved wall portions for guiding the flow of air away from the respective cross-flow blower. The air conditioner design of Laing reduces the width of the air conditioner by positioning the cross-flow blowers in a vertical stacked arrangement. However, many problems exist with the air conditioner of Laing.
One problem with the Laing air conditioner involves the blower drive. In Laing, a single motor in conjunction with a pulley system drives the two blowers. However, the pulley system has a single belt and three pulleys, one rotatably mounted on the motor and the other two rotatably mounted on the blowers. The motor is located on the same side of the air conditioner as the compressor, pump, and other components which can potentially cause a high temperature environment, reducing the belt life. Repairing or replacing the belt is difficult because of the restricted space within the motor/compressor area. To accomplish repair or replacement, the motor must be removed, which can be a complicated and time consuming task. Further, the three pulley coupling is more vulnerable to misalignment than a two pulley system because each additional pulley compounds the chance of misalignment.
It is therefore desired to provide a self contained packaged air conditioning unit wherein the blowers are driven more reliably and efficiently.
It is furthermore desired to provide a self contained packaged air conditioning unit wherein only one motor is required to drive the blowers.